The present invention relates to a charging generator controlling device which includes a switching unit and a diagnosing unit to detect and display abnormal states such as a non-power-generation state and uncontrolled state of the charging generator and for disconnecting a first rectifier output terminal when such a state is detected.
First, a conventional charging generator controlling device will be described with reference to FIG. 1. In FIG. 1, reference numeral 1 designates a three-phase AC generator, which may be mounted on a vehicle (not shown), and is driven by an engine (not shown). The AC generator includes three-phase star-connected armature coils and a field coil 102. In FIG. 1, reference numeral 2 designates a full-wave rectifier for full-wave rectifying the AC output of the generator 1; 103, 104 and 105, a first rectifier output terminal, a second rectifier output terminal and a ground terminal of the full-wave rectifier, respectively; and 3, a voltage regulator which controls the field current of the field coil 102 to thus maintain the output voltage of the generator 1 at a predetermined value V.sub.1.
The voltage regulator 3 includes as shown in FIG. 1, a surge absorbing diode 107 connected between the terminals of the field coil 102, Darlington-connected transistors 108 and 109 for selectively interrupting the current in the field coil 102, a resistor 111 forming a base circuit for the transistors 108 and 109, a control transistor 110 for turning on and off the transistors 108 and 109, a Zener diode, 113 used to detect an output voltage at the second rectifier output terminal 104 of the generator 1 and which is rendered conductive when the output voltage reaches the first predetermined value V.sub.1, resistors 112 and 114 connected in series to form a voltage divider circuit, and an initial exciting resistor 106 which is connected to a charge display lamp 6 and is used to supply initial exciting current to the generator 1 if the display lamp 6 is open circuited. Further in FIG. 1, reference numeral 4 designates a battery, and 5 a keyswitch.
The operation of the above-described conventional device will now be described.
When the keyswitch 5 is closed to start the engine, a base current is supplied from the battery 4 through the keyswitch 5 and the resistor 111 to the transistors 108 and 109, to thus render the transistors 108 and 109 conductive. When the transistors 108 and 109 are rendered conductive, a field current is supplied from the battery 4 through the keyswitch 5, the charge display lamp 6, the resistor 106, and the transistors 108 and 109 to the field coil 102, so that a field magnetomotive force is generated.
Then, when the engine is started and the generator 1 is driven thereby, AC outputs are induced in the armature coils 101 in a magnitude determined by the speed of rotation of the generator 1. The AC outputs thus induced are full-wave rectified by the full-wave rectifier 2. If the rectified output of the rectifier 2 is lower than the predetermined value V.sub.1, the potential at the voltage dividing point of the voltage divider circuit composed of the resistors 112 and 114 will be low, and therefore the Zener diode 113 will be maintained nonconductive and the field current maintained supplied. Accordingly, the output voltage of the generator 1 increases with the speed of rotation. When the speed of rotation of the generator is further increased and the output voltage becomes higher than the first predetermined value V.sub.1, the potential at the voltage dividing point of the voltage divider circuit also increases until the point that the Zener diode 106 is rendered conductive. Accordingly, base current is supplied through the Zener diode 113 to the transistor 110 to render the transistor 110 conductive. When the transistor 110 is conductive, the transistors 108 and 109 are rendered nonconductive. As a result, the current flowing to the field coil 102 is interrupted, whereupon the output voltage of the generator 1 decreases.
When the output voltage decreases to the first predetermined value V.sub.1, the Zener diode 113 and the transistor 110 are rendered nonconductive again. As a result, the field coil 102 is energized and the output voltage of the generator 1 increases again.
The above-described operation is repeatedly carried out to maintain the output voltage of the generator 1 at the first predetermined value V.sub.1. The output voltage thus controlled charges the battery 4. In this case, the output voltage at the second rectifier output terminal 104 is substantially equal to the first predetermined value V.sub.1, and thus substantially equal to the voltage of the battery 4. Accordingly, the charge display lamp 6 is turned off, thus indicating the fact that the battery 4 has been charged.
The above-described conventional device is accompanied by certain disadvantages. Particularly, if there is a break in the exciting circuit, the charge display lamp 6 will not be turned on in the case when the generator 1 generates no electric power. Accordingly, it cannot be detected whether or not the battery is satisfactorily charged, and the battery may in fact be completely discharged. In addition, it cannot be detected when the first rectifier output terminal 103 is disconnected, and the output voltage of the generator is out of control.
Another conventional charging generator controlling device will be described with reference to FIG. 2. In FIG. 2, reference numerals used in common with FIG. 1 designate like components, and hence detailed descriptions thereof will be omitted.
In this charging generator, the 3 regulator includes a surge absorbing diode 201 connected across the output terminals of the field coil 102, Darlington-connected transistors 202 and 203 for selectively interrupting the current in the field coil 102, a resistor 204 forming a base circuit for the transistors 202 and 203, a control transistor 205 for turning on and off the transistors 202 and 203, a Zener diode 206 connected to a base terminal of the control transistor 205, diodes 207 and 208 have cathodes connected together in a logical "OR" circuit arrangement and with the cathodes further being connected to the cathode of the Zener diode 206, resistors 209 and 210 connected in series to form a voltage divider circuit and series-connected resistors 211 and 212 forming a voltage divider circuit for the voltage appearing at the output of the second rectifier output terminal.
The operation of the second conventional device will now be described.
When the keyswitch 5 is closed to start the engine, base current is supplied from the battery 4 through the keyswitch 5, the display lamp 6 and the resistor 204 to the transistors 202 and 203, rendering the transistors 202 and 203 conductive. When the transistors 202 and 203 are conductive, field current is supplied from the battery 4 through the keyswitch 5, the charge display lamp 6, the field coil 102, and the transistors 202 and 203 to the field coil 102 so that a field magnetomotive force is generated.
When the engine is started and the generator 1 is driven thereby, AC outputs are induced in the armature coils 101 in a magnitude depending on the speed of rotation of the generator 1. The AC outputs thus induced are full-wave rectified by the full-wave rectifier 2. If the rectified output of the rectifier 2 is lower than the predetermined value V.sub.1, the potential at the voltage dividing point of the voltage divider circuit composed of the resistors 209 and 210 is low, and therefore the Zener diode 206 is nonconductive and field current is maintained supplied. The output voltage of the generator 1 increases with the speed of rotation. When the speed of rotation of the generator increases to the point where output voltage becomes higher than the first predetermined value V.sub.1, the potential at the voltage dividing point of the voltage divider circuit also increases, so that the Zener diode 206 is rendered conductive. Accordingly, base current is supplied through the Zener diode 206 to the transistor 205 to render the transistor 205 conductive. When the transistor 205 conducts the transistors 202 and 203 are rendered nonconductive. As a result, the current flowing to the field coil 102 is interrupted, and the output voltage of the generator 1 is decreased.
When the output voltage decreases to the first predetermined value V.sub.1, the Zener diode 206 and the transistor 205 are rendered nonconductive again. As a result, the field coil 102 is energized and the output voltage of the generator 1 increases again.
As the above-described operation is repeatedly carried out, the output voltage of the generator 1 is maintained at the first predetermined value V.sub.1. The output voltage thus controlled charges the battery 4. In this case, the output voltage at the second rectifier output terminal 104 is substantially equal to the first predetermined value V.sub.1, and thus substantially equal to the voltage of the battery 4. Accordingly, the charge display lamp 6 is turned off, thus indicating the fact that the battery 4 has been charged.
If, in this case, the voltage of the battery 4 cannot be detected, for instance because of breakage of the wiring between the battery 4 and the resistor 209, the voltage at the second rectifier output terminal 104 is detected with the resistors 211 and 212 and maintained at the second predetermined value V.sub.2 higher than the first predetermined value V.sub.1.
An object of the invention is thus to provide a charging generator controlling device in which the above-described difficulties accompanying conventional charging generator controlling devices are eliminated.